Simulation And Application Of Solid-Liquid Coupled Heat Transfer In Internal Combustion Engines

It is one of most important groundworks to study heat transfer and thermal status of engines' components for engine thermal fatigue and thermal equilibrium investigation. Finite volume method (FVM) makes it realizable to simulate the coupled heat transfer between liquid and solid. Based on analysis of heat transfer simulation characters between main engine heated parts, piston-liner-coolant-body fluid-solid coupled system is created. This coupled system concludes coupled heat transter between solid and solid, besides coupled heat transfer and flow simulation between fluid and solid. Outer boundary conditions between single parts are converted to inner boundary conditions processed through finite software, so that heat transfer simulation becomes more reasonable and simpler. With the coupled simulation model, heat transfer of stable working state, periodic transient working state and exchanging working state including cool start, full load and full speed were simulated. Futhermore, combined with engine working process simulation code, engine heat balance was worked out.Major contents of this thesis can be list as:1. By heat transfer feature analysis of enignes' key heated components, piston-liner-coolant-body fluid-solid coupled heat transfer simulation model for dryliner and wetliner were constructed. Stable heat transfer and fluid flow in rated mode and maximum torque mode were conducted. The temperature fields of piston and liner in rated mode were measured, which verified that the simulation model is reasonable.2. For the high-frequency periodic character of engines' heat transfer, the thermal status of gas in cylinder changing periodically and piston's back and forth movement was analysed and dynamic contact heat transfer model for the piston andliner was set up. Periodic transient heat transfer simulations of piston-liner-coolant-body fluid-solid were calculated. The primary distribution principles of temperature field of cylinder's key components were worked out. The integral influence of engines' periodic to the coupled system was anlysed.3. The transient heat transfer and fluid flow of coupled system during engine cool start, full load and full speed were simulated. The development principle of coupled system's temperature field and fluid flow according as time was worked out, which is one of the major reliance to establish a reasonable heat management strategy.4. Based on former heat transfer simulation work, a heat balance simulation module was coded and heat balance of the engine when working through full load and full speed feature were simulated. By comparison to the test result, it is concluded that the coupled simulation system model is a reasonable and efficient method for engines' heat transfer.It is one of most important groundworks to study heat transfer and thermal status of engines' components for engine thermal fatigue and thermal equilibrium investigation. Finite volume method (FVM) makes it realizable to simulate the coupled heat transfer between liquid and solid. Based on analysis of heat transfer simulation characters between main engine heated parts, piston-liner-coolant-body fluid-solid coupled system is created. This coupled system concludes coupled heat transter between solid and solid, besides coupled heat transfer and flow simulation between fluid and solid. Outer boundary conditions between single parts are converted to inner boundary conditions processed through finite software, so that heat transfer simulation becomes more reasonable and simpler. With the coupled simulation model, heat transfer of stable working state, periodic transient working state and exchanging working state including cool start, full load and full speed were simulated. Futhermore, combined with engine working process simulation code, engine heat balance was worked out.Major contents of this thesis can be list as:1. By heat transfer feature analysis of enignes' key heated components, piston-liner-coolant-body fluid-solid coupled heat transfer simulation model for dryliner and wetliner were constructed. Stable heat transfer and fluid flow in rated mode and maximum torque mode were conducted. The temperature fields of piston and liner in rated mode were measured, which verified that the simulation model is reasonable.2. For the high-frequency periodic character of engines' heat transfer, the thermal status of gas in cylinder changing periodically and piston's back and forth movement was analysed and dynamic contact heat transfer model for the piston andliner was set up. Periodic transient heat transfer simulations of piston-liner-coolant-body fluid-solid were calculated. The primary distribution principles of temperature field of cylinder's key components were worked out. The integral influence of engines' periodic to the coupled system was anlysed.3. The transient heat transfer and fluid flow of coupled system during engine cool start, full load and full speed were simulated. The development principle of coupled system's temperature field and fluid flow according as time was worked out, which is one of the major reliance to establish a reasonable heat management strategy.4. Based on former heat transfer simulation work, a heat balance simulation module was coded and heat balance of the engine when working through full load and full speed feature were simulated. By comparison to the test result, it is concluded that the coupled simulation system model is a reasonable and efficient method for engines' heat transfer.